Typical, right? Most kids today do their homework with only one eye on the book. The other's on the computer screen, watching for Instant Messages or MySpace updates; meanwhile, fingers are tapping out return messages, and the steady beat of music coming through iPod earbuds is interrupted only by the regular pinging of cell phones announcing new text messages. A recent Los Angeles Times/Bloomberg Poll found that 53 percent of kids 12–17 did at least one other thing while studying, while 21 percent performed three other tasks simultaneously.

Parents, save this msg: UCLA Associate Professor of Psychology Russ Poldrack is here to tell you that this isn't a good idea.

Poldrack, with fellow team members Karin Foerde M.A. '02 and Barbara J. Knowlton, recently published the results of a multitasking experiment in which 14 men and women in their 20s were asked to learn a simple classification task under two sets of circumstances: once with no distractions, and then while simultaneously counting the number of high-pitched beeps they heard through headphones. In both cases, subjects learned the new skill just fine. But the study, using MRI scans, showed that when asked to multitask, the subjects used a totally different part of their brains — the striatum rather than the hippocampus.

There's a big difference. The hippocampus, says Poldrack, oversees the development of "declarative memory" — the kind of remembering that allows you to learn a fact, then later retrieve it and apply it to a new situation. By contrast, the striatum governs behavioral tendencies and habits, and information processed in this region is less "flexible"; that is, less usable out of context.

"Imagine that you always drive to work the same way," explains Poldrack. "The 'autopilot' that guides you is what we mean by habit. But if one day there's a roadblock and Wilshire Boulevard is closed, your autopilot can't give you an alternative way to travel. You need to have a flexible knowledge of what streets in Los Angeles go where to help you figure out what to do."

Poldrack notes that listening to music or watching TV are not "the kinds of demanding distractions we presented." But learning something new while doing stuff that requires an active response — say, updating MySpace bulletin boards — is exactly like trying to study while counting high-pitched beeps. That kind of learning might enable a kid to memorize the names and dates of major Civil War battles — but be flummoxed when asked almost the same thing a different way, such as "name the important events of 1863."

In other words, if you or your kids want to learn something permanently and usefully, do something very old school: Shut up, sit still, and pay attention.